Answer:
Current monthly payment on their existing mortgage would be $1158.66
Step-by-step explanation:
Total cash value = $160,000
Down payment = 10% of 160,000
Down Payment = $16,000
Balance amount = 160,000 - 16,000 = $144,000
Monthly payment formula:

where,
PV is present value of home, PV=$144,000
r is rate per period , 
n is number of period, n=30x12 = 360


Monthly payment would be same for 30 years.
Thus, Current monthly payment on their existing mortgage would be $1158.66